Printed decorative surface coverings

ABSTRACT

The present invention relates to a primer layer to improve the printability of floor or wall covering by aqueous ink compositions, the primer layer comprising one or more acrylic copolymers and silica and the covering comprising polyvinyl chloride.

FIELD OF THE INVENTION

The present invention relates to decorative floor and wall coveringscomprising a printed-on thermoplastic material. The invention furtherrelates to a method for the production of such surface coverings.

STATE OF THE ART

In recent years, printed building panels have gained increasing success.These types of decorative floor and wall panels usually comprise athermoplastic substrate and a protective layer. The thermoplasticmaterial is often polyvinyl chloride. The substrate is printed with apattern resembling natural stone, wood, ceramics etc. The pattern isoften printed by rotogravure printing or direct printing. However,rotogravure printing or direct printing does not offer the desiredflexibility in changing design of the patterns and adapting patterns fordifferent needs of clients. Furthermore, a certain repetition of thepattern cannot be avoided by rotogravure printing or direct printing.

Recently digital printing has offered new possibilities to the flooringindustry to customize decorative patterns for floor and wallapplications and to print small quantities of substrates. By digitalprinting is conventionally meant printing by means of non-contactprinting, for example using a Drop-on-Demand (DOD) technique. A drop ofink is placed with great accuracy on a surface. Examples of DODtechniques are piezoelectric DOD inkjet and thermal DOD inkjet. In apiezoelectric DOD inkjet printer, the piezoelectric material changesshape when a voltage is applied. The change of shape of thepiezoelectric material generates a pressure pulse in the fluid, therebyejecting a droplet of ink from the nozzle. In a thermal DOD inkjetprinter, ink drops are ejected by forming an ink vapor bubble by heatingthe ink.

Digital printers use one of two methods to print: single-pass andmulti-pass. In the first case, the surface to be printed is fed in asingle pass over four print heads, representing the four primary colors(cyan, magenta, yellow and black), which results in faster printing. Inmulti-pass, the same surface travels a longer path since it goes throughfour successive passes (one per color). Multi-pass reduces the cost ofthe printer since there's only one drum for all the primary colors,whereas with single-pass, there has to be one drum per primary color,but of course printing times are at least four times as long.

Single-pass digital printing has become quite advanced over the last fewyears and have emerged to challenge conventional technologies in manysectors.

Different kind of inks may be used for digital printing, such as UVcurable inks, solvent based inks and aqueous inks (also calledwaterborne or water based inks). When printing on a thermoplasticsubstrates such as a substrate adapted to from decorative surfacecoverings, printing is facilitated by using UV curable inks or solventbased inks compared to aqueous inks. Printing with an aqueous ink on athermoplastic substrate has proved to be difficult. A drop of an aqueousink does not stay but tends to bleed on the thermoplastic surface,resulting in a print of low quality. However, due to environmentalreasons, it is favorable to replace UV curable inks and solvent basedinks.

The single-pass DOD representing huge time savings when compared tomulti-pass DOD and other printing technologies, is more sensitive tobleeding, and images containing a multitude of white lines, distributedover the whole of the image, are obtained especially when aqueous inksare applied.

In order to provide an improved print on a thermoplastic material,obtained from digital printing of an aqueous pigment ink, US2014/0144583 discloses an aqueous solution comprising a salt, preferablyat least one metal salt, for being used as a primer before the digitalprinting step.

The metal salt may be a monovalent metal salt, for example comprising amonovalent ion such as Na. The metal salt may be a polyvalent metalsalt. Preferably, the polyvalent metal salt comprises divalent ions suchas Ca²⁺, Cu²⁺, Ni²⁺, Mg²⁺, Zn²⁺, or Ba²⁺, or trivalent ions such as Al³⁺or Fe³⁺. The metal salt may for example be sodium chloride or calciumchloride. The salt may also be a non-metal salt such as ammoniumchloride.

AIMS OF ASPECTS OF THE INVENTION

According to an aspect of the present invention it is aimed at providinga primer composition enabling the production of printed decorative floorand wall coverings comprising high quality images obtained by digitalprinting, more particularly single-pass digital printing, of aqueouspigment inks.

According to a second aspect of the present invention, it is aimed atproviding printed decorative floor and wall coverings comprising such aprimer.

According to a third aspect of the present invention it is aimed atproviding a method for producing a printed decorative floor or wallcoverings.

SUMMARY OF THE INVENTION

The present invention discloses a primer layer to improve theprintability of floor or wall covering by aqueous ink compositions, theprimer layer comprising one or more acrylic copolymers and silica andthe covering comprising polyvinyl chloride.

Preferred embodiments of the present invention include one or more ofthe following features:

-   the primer layer comprises from 15 to 35% by weight, preferably from    20 to 30% by weight of silica and from 40 to 80% by weight,    preferably from 50 to 75% by weight, more preferably from 60 to 70%    by weight of one or more acrylic copolymer;-   the silica is characterized by a d50 particle size, as determined by    the laser light scattering granulometry technique, according to ISO    13320-1, comprised between 4.5 and 14 μm, preferably between 5.5 and    12 μm, more preferably between 6.5 and 10 μm;-   the silica is characterized by a BET specific surface according to    ISO 9277 of at least 350 m²/g, preferably at least 450 m²/g, more    preferably at least 550 m²/g, most preferably at least 650 m²/g.

The present invention further discloses a printed decorative surfacecovering comprising the primer layer wherein the thickness of the primerlayer is comprised between 5 and 30 μm, preferably between 5 and 25 μm,more preferably between 5 and 20 μm.

The present invention also discloses a printed decorative surfacecovering comprising two or more assembled substrates, each of thesubstrates being coated with the primer layer, the primer layer beingcovered by a print layer.

The present invention further discloses a method for the preparation ofthe decorative surface covering, the method comprising the steps of:

-   -   providing a polyvinyl chloride substrate;    -   applying the primer layer;    -   printing, preferably by digital printing, a print on the primer        layer with an aqueous pigment ink composition;    -   drying and/or curing the aqueous pigment ink composition to form        the printed substrate.

Preferred embodiments of the method for the preparation of thedecorative surface covering include one or more of the followingfeatures:

-   the primer layer is obtained from drying a primer composition    comprising an acrylic copolymer dispersion, preferably an anionic    acrylic copolymer dispersion comprising silica, the acrylic    copolymer dispersion being characterized by a Minimum Film Forming    Temperature, according to ASTM D2354, comprised between 10 and    60° C. and preferably between 15 and 50° C.;-   an additional step of the method comprises contacting the printed    substrate with a protecting layer the protecting layer comprising a    thermoplastic material;-   the protective layer is contacted with the printed substrate through    a calendaring process or a coating process;-   an additional step comprises contacting the protective layer with a    topcoat layer the topcoat layer comprising a cross-linked material;-   the topcoat layer is obtained from curing a radiation curable    coating composition, the radiation curable composition comprising    ethylenically unsaturated acrylic, ester, ether or urethane    comprising polymers, oligomers or monomers;-   the aqueous pigment ink composition is printed by a single-pass    digital printer;-   an additional step comprises performing mechanical embossing at a    surface temperature comprised between 100° C. and 200° C.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides decorative floor and wall coveringscomprising high quality prints, obtained from digital printing, inparticular from single-pass digital printing, of aqueous pigment inks onthermoplastic substrates.

According to a first aspect of the present invention a primerformulation for application on thermoplastic substrates is provided, theprimer formulation enabling high quality prints on the thermoplasticsubstrates. The primer formulation of the present invention comprises anacrylic copolymer dispersion and silica.

The copolymer dispersions for being used in the primer composition ofthe present invention may be obtained by copolymerization ethylenicallyunsaturated monomers in aqueous emulsion in the presence of non-ionic,cationic or anionic surfactants. Preferably the copolymer dispersionsare anionic copolymer dispersions wherein the anionic surfactants arehigher fatty alcohol sulfates such as for example sodium or potassiumlauryl sulfate.

The acrylic copolymers of the acrylic copolymer dispersions in generalcomprise from 10 to 90% by weight, preferably from 20 to 80% by weightof (meth)acrylic acid esters, from 5 to 40% by weight, preferably from10 to 30% by weight of ethylenically unsaturated mono- or diacids, from0 to 50% by weight, preferably from 5 to 40% by weight of ethylenicallyunsaturated monomers other than (meth)acrylates and ethylenicallyunsaturated mono- or diacids.

Examples of (meth)acrylic acid esters that may be used for preparing thecopolymers of the present invention are methyl, ethyl, propyl,isopropyl, butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, octyl,dodecyl, octadecyl, octenyl and stearyl (meth)acrylate.

Examples of ethylenically unsaturated mono- or diacids are (meth)acrylicacid, crotonic acid, maleic acid, fumaric acid, itaconic acid,citraconic acid, senecioic acid and the monoalkyl esters the diacids.

Examples of ethylenically unsaturated monomers other than(meth)acrylates that may be incorporated in the copolymers of thepresent invention are ethylene, propylene, butylene, isobutylene, vinylchloride, vinylidene chloride, (meth)acrylonitrile, styrene, α-methylstyrene, vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate,vinyl isobutyrate, vinyl valerate, vinyl 2-ethylhexanoate, vinylisooctanoate, vinyl nonoate, vinyl decanoate, vinyl pivalate, vinylversatate, cetylvinyl ether, dodecylvinyl ether, di-butyl maleate,di-2-ethylhexyl maleate, acrylamide, methacrylamide,N(hydroxymethyl)-acrylamide, N-isopropyl acrylamide, vinylsulfonic acid,2-acrylamido-2-methylpropanesulfonic acid, styrene-p-sulphonic acid andallylalcohol

The acrylic copolymer optionally may comprise up to 3% by weight, basedon the monomer mixture, of cross-linking monomers.

Examples of I cross-linking monomers are methylene-bis-acrylamides,methylene-bis-methacrylamides, diacrylates, polyacrylates,dimethacrylates and polymethacrylates of dihydric or polyhydricC₂-C₆-alcohols, divinyldioxane, diallyl phthalate, diallyl ethers ortriallyl ethers of dihydric or polyhydric alcohols, especially ofpentaerythritol, and diacrylates and dimethacrylates of polyethyleneglycols and polypropylene glycols.

The copolymer dispersions preferably used in the primer formulation ofthe present invention are characterized by a solid content comprisedbetween 20 and 65% by weight, preferably between 25 and 60% by weight,more preferably between 30 and 55% by weight and most preferably between35 and 50% by weight.

The acrylic copolymer dispersions, used in the primer of the presentinvention, are characterized by a Minimum Film Forming Temperature,according to ASTM D2354, comprised between 10 and 60° C. and preferablybetween 15 and 50° C.

The Minimum Film Forming Temperature of the acrylic copolymerdispersion, according to ASTM D2354, is at most 20° C., preferably atmost 15° C., more preferably at most 10° C., most preferably at most 5°C. higher than the casting temperature of the acrylic copolymercomprising film, as measured in an air ventilated oven.

Advantageously the casting temperature of the acrylic copolymercomprising film, as measured in an air ventilated oven, is at least 20°C., preferably at least 15° C., more preferably at least 10° C. and mostpreferably at least 5° C. higher than the Minimum Film FormingTemperature of the acrylic dispersion, according to ASTM D2354.

The primer formulation of the present invention comprises the acryliccopolymer dispersion in an amount comprised between 40 and 80% byweight, preferable between 50 and 75% by weight, more preferably between60 and 70% by weight of the total weight of the primer formulation.

The silica for being used in the primer composition of the presentinvention is characterized by a particle size, d50, as determined by thelaser light scattering granulometry technique, according to ISO 13320-1,comprised between 4.5 and 14 μm, preferably between 5.5 and 12 μm, morepreferably between 6.5 and 10 μm.

The silica is further characterized by a BET specific surface (accordingto the Brunauer-Emmett-Teller Surface Area Analysis) according to ISO9277 of at least 350 m²/g, preferably at least 450 m²/g, more preferablyat least 550 m²/g or less, most preferably at least 650 m²/g.

The silica further is characterized by a high porosity, measured as DOAabsorption capacity. For highly porous particles, because of the smalldimensions of the pores, liquids are drawn inside the pores by capillaryforces. Due to this purely physical absorption process the absorption isindependent of the chemical nature of the liquid to absorb. In generaldioctyl adipate (DOA) is used.

The DOA absorption capacity of the silica is comprised between 200 and300 ml, preferably between 220 and 290 ml, more preferably between 240and 280 ml, most preferably between 250 and 270 ml per 100 g of silica.

The primer formulation comprises silica in an amount comprised between 2and 20% by weight, preferably between 5 and 15% by weight of the totalweight of the primer formulation.

The primer formulation of the present invention further comprises one ormore dispersing additives in an amount comprised between 1 and 4% byweight, preferably between 1.5 and 3.5% by weight of the total weight ofthe primer formulation.

Examples of dispersing additives are the sodium salt of anaphthalenesulfonic acid-formaldehyde condensation product, e.g.2,2′-dinaphthylmethane-6,6′-disulfonic acid, sodium salt; aliphaticamines and salts thereof, e.g. containing a long chain aliphatic group,e.g., hexadecyltrimethyl ammonium chloride; or alkylphenolpolyglycolethers as e.g., nonylphenolpolyglycol ethers or isooctylphenolpolyglycolether (e.g., p-nonylphenol or p-isooctylphenolethylene oxide adductshaving 10 to 20 ethylene oxide units per molecule).

The primer formulation of the present invention further may comprise oneor more antifoaming additives in an amount comprised between 0.2 and 2%by weight, preferably between 0.5 and 1.5% by weight of the total weightof the primer formulation.

Examples of antifoaming agents are polysiloxanes, such aspolymethylhydrogensiloxane or polydimethylsiloxane, polyoxyalkylenepolysiloxane block copolymers, grafted polyoxyalkylene polysiloxaneblock copolymers and mixtures thereof with organic oils such as mineraloils such as naphthenic and paraffinic mineral oil, polypropylene oxide,polybutadiene, certain oils of vegetable or animal origin, and the like.

To the primer formulation of the present invention, water may be addedin order to reduce its final viscosity to a value comprised between 50and 700 mPa·s, preferably between 100 and 600 Pa·s, more preferablybetween 200 and 500 mPa·s, as measured by a Brookfield viscometer at 25°C. (spindle 4 at 50 rpm).

The water quantity added, in general is comprised between 5 and 35% byweight, preferably between 10 and 30% by weight, more preferably between15 and 25% by weight of the total weight of the primer formulation.

To the primer formulation further may comprise high boiling alcoholswhich are added in such an amount that they comprise less than 10% byweight, preferably 7% by weight, more preferably less than 5% by weightof the total weight of the primer composition. High boiling alcohols ingeneral are added in order to manage the evaporation speed of the primerformulation upon application. Examples of high boiling alcohols areglycerol and sorbitol,

The manner wherein the primer formulation is prepared or the order inwhich the constituents are mixed with each other is not significant. Theimportant criterion is that mixing is thorough to form a homogeneousdispersion.

According to a second aspect of the present invention, printeddecorative floor and wall coverings are provided comprising a substratecoated with a primer layer, the primer layer being covered by a printlayer wherein the primer layer comprises one or more acrylic copolymersand silica.

The substrate comprises a thermoplastic material such as polyvinylchloride, polyester, polypropylene, polyethylene, polystyrene,polyurethane, polyethylene terephthalate, polyacrylate, polyvinylbutyral, or a combination thereof. The substrate may further compriseadditives such as a plasticizer. The substrate may be in form of athermoplastic foil or film. The substrate may be transparent, colored oropaque. The color of the carrier may form a base color for the print.

The decorative surface of the present invention may comprise two or moreassembled substrates, each of the substrates being coated with a primerlayer and a print layer, wherein the primer and the print is providedeither on the upper or on the lower surface of the two or moresubstrates.

Alternatively, the substrate layer comprises a primer layer and a printon both of its surfaces. Same pattern or design may be printed on bothsurfaces of the substrate. Alternatively, the print or design may bedifferent.

The decorative floor and wall covering further comprises a protectinglayer, the protecting layer comprising a thermoplastic material.

The protective layer may be a foil or film comprising a thermoplasticmaterial such as polyvinyl chloride, polyester, polypropylene,polyethylene, polystyrene, polyurethane, polyethylene terephthalate,polyacrylate, polyvinyl butyral, or a combination thereof. Theprotective layer may further comprise additives such as a plasticizer.

The protective layer comprising thermoplastic material, is arranged onand bonded to the printed substrate.

In a preferred embodiment a topcoat layer comprising cross-linkedmaterial, preferably obtained from cross-linking radiation curablecoating compositions, is arranged on a protective layer, comprisingthermoplastic material, in order to improve the wear resistance andchemical resistance of the protective layer comprising thermoplasticmaterial.

The topcoat layer may be a cross-linked layer such as a cross-linkedcoating preferably obtained from curing a radiation curable coatingcomposition, the radiation curable composition comprising ethylenicallyunsaturated polyacrylate, polyester or polyurethane polymers and/oroligomers and optionally ethylenically unsaturated monomers. Wearresistant particles such as aluminium oxide particles may be included inthe cross-linked topcoat layer. The cross-linked topcoat layer ispreferably transparent. The topcoat layer comprising cross-linkedmaterial, is arranged on to the protective layer.

The decorative floor and wall coverings of the present invention mayinclude a reinforced layer, comprising a carrier, such as a glass matand/or non-woven and a thermoplastic material.

The decorative floor and wall coverings of the present invention may beprovided with a baking layer.

The backing layer may comprise a thermoplastic material such aspolyvinyl chloride, polyester, polypropylene, polyethylene, polystyrene,polyurethane, or polyethylene terephthalate. The baking layer mayfurther comprise fillers, for example calcium carbonate, and additivessuch as plasticizer, impact modifier, stabilizer, processing aids,pigment, lubricants etc. Alternatively, the baking layer may be a WoodPlastic Composite comprising a thermoplastic binder and wood fibers orparticles.

The primer layer, obtained from the primer composition of the presentinvention, comprises between 15 and 35% by weight, preferably between 20and 30% by weight of silica, from 60 to 80% by weight, preferably from65 to 75% by weight of acrylic copolymer and from 1 to 10% by weight,preferably from 2 to 8% by weight of dispersing and antifoamingadditives.

The thickness of the primer layer is comprised between 5 and 30 μm,preferably between 5 and 25 μm, more preferably between 5 and 20 μm.

The ink comprises dyes and/or pigments giving the ink its specificcolor, optionally silica particulates and optionally one or morebinders. Alternatively, the pigment may be coated by a binder. Thebinder preferably is a polymer such as for example styrene,(meth)acrylic (co)polymer, or unsaturated monomers, polyesters, vinyl(co)polymers, aromatic and aliphatic polyurethanes, or alkyd resins.

The print may be a decorative design. The decorative design may benatural designs and patterns such as a wood pattern or stone pattern.The decorative design may also be a fantasy design or pattern or aphotograph.

According to a third aspect of the present invention a method forproducing printed decorative floor and wall coverings is provided.

The method comprises:

-   providing a substrate;-   applying a primer composition comprising at least one acrylic    copolymer dispersion and silica salt on a surface of the substrate;-   drying the primer formulation to form the primer layer;-   printing, preferably by digital printing, a print on the primer    layer with an aqueous pigment ink composition;-   drying and/or curing the aqueous pigment ink composition formulation    to form the printed substrate.

Prior to the application of the primer composition, the substrate may bepre-treated by corona, flaming or plasma.

The primer composition is applied on the substrate by any method forliquid coating application, known in the art, such as curtain coating,roller application or spray coating.

The step of drying the primer composition comprises applying heat to theprimer composition. Heat may be applied in form of for instance mediumand/or short infrared irradiation and/or heated air.

The aqueous pigment ink is printed by a digital printing process. Theprinter is preferably an inkjet printer. Preferably, the printer is aDOD (Drop on Demand) piezo-electric inkjet printer. In particular theprinter is a single pass DOD (Drop on Demand) piezo-electric inkjetprinter. A thermal DOD inkjet printer may also be used.

The step of drying- and/or curing the aqueous pigment ink compositioncomprises applying heat to the aqueous ink composition. Heat may beapplied in form of for instance medium and/or short infrared irradiationand/or heated air.

After the primer has been dried, the primed substrate may be rolled on aroller for storage until printing.

Alternatively, after the print has been dried and/or cured, the printedsubstrate may be rolled on a roller for storage until furtherprocessing.

In an additional step, the method of the present invention comprisescontacting a protective layer, comprising a thermoplastic material withthe printed surface of the substrate.

The process for contacting a thermoplastic protecting layer with theprinted substrate comprises a calendaring, a lamination or aco-extrusion process, among others.

In an additional step, the method of the present invention comprisescontacting a topcoat layer, comprising a cross-linked material, with theprotective layer.

The process for contacting a cross-linkable topcoat layer with thethermoplastic protection layer comprises any liquid coating applicationtechnique, known in the art, such as curtain coating, roller applicationor spray coating.

The primer of the present invention prevents the ink drops fromaccumulating and mixing into large ink drops so that a print of highquality, made by digital printing of an aqueous pigment ink composition,is obtained.

The primer and the print do not reduce the bonding strength between theprinted substrate and the protective layer.

Furthermore, the print is not affected when contacting the printedsubstrate with the protective layer. The primer has already agglomeratedthe ink such that the ink drops are fixed on the substrate and notaffected by the contacting with subsequent layers.

In an additional step the method of the present invention comprisespressing the substrate, having the print thereon and the protectivelayer with an embossed press plate. The embossing temperature iscomprised between 100 and 200° C. A printed decorative surface having anembossed structure thus is formed.

Embossing preferably is performed before application and cross-linkingof the topcoat layer, or after application and before cross-linking ofthe topcoat layer.

EXAMPLES

The following illustrative examples are merely meant to exemplify thepresent invention but is not destined to limit or otherwise define thescope of the present invention.

Example 1

Primer composition.

625.9 parts of Neocryl® XK 151, 39.0 parts of glycerol, 29.5 parts ofTego® Dispers 650, 11.0 parts of Tego® Foamex 842 and 184.1 parts ofwater were placed in a lab beaker provided with an electronic overheadlab mixer. Subsequently 110.5 parts of Sipernat® 310 were slowly addedwhile stirring at 3000 rpm with a 6 cm diameter disc disperser. Aftercompletion of the silica addition the mixture is further stirred for 3minutes until a homogeneous primer composition is obtained.

Example 2

Printed substrate with primer.

A polyvinyl chloride substrate for decorative surface applications, wascoated with the primer of example 1. After drying in an air ventilatedoven at 80° C. for 6 seconds a primer layer with a coating thickness of5 μm was obtained.

The substrate, comprising the primer, was printed by means of a singlepass digital printer with a water based ink. The print was dried during3 seconds at 80° C. in an air ventilated oven. The printed substrate wasbonded to a transparent protective polyvinyl chloride foil in ahot/cold-pressing step at 170° C. for 60 seconds at approximately 7 barpressure, followed by cooling down to 25° C. at approximately 2 barpressure. The printed image is fixated evenly over the surface of thesubstrate and a print result with good colour strength and resolution isachieved. The bonding between the printed substrate and the protectivefoil was good.

Comparative Example

Printed substrate without primer.

A polyvinyl chloride foil for decorative surface applications, wasprinted directly on by means of a digital printer with a water basedink. The print was dried during 1 minute at 80° C. in an air ventilatedoven. The printed foil was bonded to a transparent protective polyvinylchloride foil in a hot/cold-pressing step at 170° C. for 60 seconds atapproximately 7 bar pressure, followed by cooling down to 25° C. atapproximately 2 bar pressure. The bonding between the printed PVC foiland the protective foil was good.

The resulting print is of poor quality. The ink drops have agglomeratedto large ink drops. The ink drops have started to bleed into each other.

1. Primer layer to improve the printability of floor or wall covering byaqueous ink compositions, said primer layer comprising one or moreacrylic copolymers and silica and said covering comprising polyvinylchloride.
 2. The primer layer according to claim 1 comprising from 15 to35% by weight, of silica and from 40 to 80% by weight, of one or moreacrylic copolymer.
 3. The primer layer according to claim 1 wherein thesilica is characterized by a d50 particle size as determined by thelaser light scattering granulometry technique, according to ISO 13320-1,comprised between 4.5 and 14 μm.
 4. The primer layer according to claim1 wherein the silica is characterized by a BET specific surfaceaccording to ISO 9277 of at least 350 m2/g.
 5. A printed decorativesurface covering comprising a polyvinyl chloride substrate coated with aprimer layer as claimed in claim 1, the polyvinyl chloride substratecoated with a primer carrying a print applied directly thereon.
 6. Aprinted decorative surface covering according to claim 5, wherein thethickness of the primer layer is comprised between 5 and 30 μm.
 7. Theprinted decorative surface covering according to claim 6, comprising twoor more assembled substrates, each of said substrates being coated witha primer layer according to claim 1, said primer layer being covered bya print layer.
 8. Method for the preparation of the decorative surfacecovering according to claim 5, comprising the steps of: providing apolyvinyl chloride substrate; applying the primer layer; printing aprint on said primer layer with an aqueous pigment ink composition;drying and/or curing the aqueous pigment ink composition to form aprinted substrate.
 9. The method according to claim 8 wherein the primerlayer is obtained from drying a primer composition comprising an acryliccopolymer dispersion, said acrylic copolymer dispersion beingcharacterized by a Minimum Film Forming Temperature, according to ASTMD2354, comprised between 10 and 60° C.
 10. The method according to claim8 comprising the additional step of contacting the printed substratewith a protecting layer said protecting layer comprising a thermoplasticmaterial.
 11. The method according to claim 8 wherein the protectivelayer is contacted with the printed substrate through a calendaringprocess or a coating process.
 12. The method according to claim 8comprising the additional step of contacting the protective layer with atopcoat layer said topcoat layer comprising a cross-linked material. 13.The method according to claim 8, wherein the topcoat layer is obtainedfrom curing a radiation curable coating composition, said radiationcurable composition comprising ethylenically unsaturated acrylic, ester,ether or urethane comprising polymers, oligomers or monomers.
 14. Themethod according to claim 8, wherein the aqueous pigment ink compositionis printed by a single-pass digital printer.
 15. The method according toclaim 8, comprising the additional step of performing mechanicalembossing at a surface temperature comprised between 100° C. and 200° C.16. The primer layer according to claim 1 comprising from 20 to 30% byweight of silica and from 50 to 75% by weight, of one or more acryliccopolymer.
 17. The primer layer of claim 16, comprising from 60 to 70%by weight of one or more acrylic copolymer.
 18. The primer layeraccording to claim 1 wherein the silica is characterized by a d50particle size as determined by the laser light scattering granulometrytechnique, according to ISO 13320-1, comprised between 5.5 and 12 μm.19. The primer layer according to claim 1 wherein the silica ischaracterized by a d50 particle size as determined by the laser lightscattering granulometry technique, according to ISO 13320-1, between 6.5and 10 μm.
 20. The primer layer according to claim 1 wherein the silicais characterized by a BET specific surface according to ISO 9277 of atleast 450 m2/g.
 21. The primer layer according to claim 1 wherein thesilica is characterized by a BET specific surface according to ISO 9277of at least 550 m2/g.
 22. The primer layer according to claim 1 whereinthe silica is characterized by a BET specific surface according to ISO9277 of at least 650 m²/g.
 23. A printed decorative surface coveringaccording to claim 5, wherein the thickness of the primer layer iscomprised between 5 and 25 μm.
 24. A printed decorative surface coveringaccording to claim 5, wherein the thickness of the primer layer iscomprised between 5 and 20 μm.
 25. The method of claim 8 wherein theprinting is by way of digital printing.
 26. The method according toclaim 9 wherein the acrylic copolymer dispersion comprises an anionicacrylic copolymer dispersion comprising silica, said Minimum FilmForming Temperature, according to ASTM D2354, comprised between 15 and50° C.